Salinity Stress In Rice Research Articles

Mitigation of Salinity Stress in Rice with Compost

Mitigation of Salinity Stress in Rice with Compost

An insight into variability and association among yield and its components under alkalinity and inland salinity stress in rice (Oryza sativa L.)

An experiment was conducted to study the variability, correlation, direct and indirect effects of yield and its attributing traits in 36 genotypes and to identify suitable parents for breeding of alkalinity and inland salinity stress tolerant lines at ARS, Kampasagar, Nalgonda during rabi, 2021-22. Analysis of variance revealed plenteous quantum of variation among the tested genotypes. Wide variation, high PCV, GCV, heritability and genetic advance were observed for seedling mortality, sterility percentage and number of filled grains per panicle. Number of productive tillers/hill and number of filled grains per panicle had a positive and significant correlation with yield whereas seedling mortality and sterility percentage had a negative and significant association with yield. Path analysis inferred that traits such as number of productive tillers/hill, number of grains per panicle and 1000 grain weight had a positive direct effect on yield. Hence,priority should be given to the above mentioned traits to develop alkalinity and inland saline tolerant rice cultivars. Lines CT118911, Sahel177, M202, and KPS10654 were found promising to be utilized as tolerant parents in the breeding programmes.

Seedling Stage Image-Based Phenotyping Selection Criteria through Tolerance Indices on Drought and Salinity Stress in Rice

Seedling Stage Image-Based Phenotyping Selection Criteria through Tolerance Indices on Drought and Salinity Stress in Rice

Exogenous riboflavin (vitamin B2) application enhances salinity tolerance through the activation of its biosynthesis in rice seedlings under salinity stress

Salinity stress triggers the accumulation of reactive oxygen species (ROS), leading to impaired plant growth. Riboflavin (RIB; vitamin B2) is synthesized by plants, fungi, and microorganisms and is a precursor of the coenzymes, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), which are important for cellular metabolism. In this study, we aimed to elucidate the mechanistic basis of the RIB-mediated alleviation of salinity stress in rice. We observed higher biomass accumulation and lower concentrations of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in RIB-pretreated seedlings under salinity stress. In vitro assays showed that H2O2 was scavenged as the RIB concentration increased, implying that RIB may function as a non-enzymatic antioxidant in ROS detoxification. RIB-pretreated seedlings accumulated more Na+ in the roots than in the leaf blades because of the contributions of OsHKT2;1, OsNHX1, and OsHKT1;4 in the roots and leaf sheaths, respectively. Liquid chromatography-mass spectrometry (LC-MS/MS) analysis revealed increased RIB concentration in roots and shoots and upregulation of key genes (OsRIBA1, OsGCHI, OsLS, and OsRS) involved in RIB biosynthesis in the roots of RIB-pretreated seedlings. Taken together, our findings suggest that RIB pretreatment ameliorates salinity stress in rice by improving (1) oxidative stress tolerance, as increased RIB concentration may function as a non-enzymatic antioxidant, and (2) ionic stress tolerance, as RIB pretreatment limits Na+ accumulation in the leaf blades and maintains a favorable Na+/K+ balance.

Genetic Variability and Association Analysis for Yield and its Components in Alkaline and Inland Saline Stress in Rice (Oryza sativa L.)

The experiment was conducted at Agricultural Research Station, Kampasagar, Nalgonda, Telangana, India during the rabi season (December, 2020 to May, 2021) to identify suitable lines tolerant to alkalinity and inland salinity stress in rice. Analysis of variance evinced plenteous quantum of variability in all the 36 genotypes investigated. Phenotypic coefficients of variation were higher than genotypic coefficients demonstrating the effect of the prevalent stress environment. High estimates of genotypic coefficient of variation, phenotypic coefficient of variation, heritability, and genetic advance as percent mean was observed for the traits, seedling mortality, number of filled grains panicle-1 and sterility %. These findings suggested the preponderance of additive gene action for these characters. The remaining traits were mostly under the influence of non-additive gene effects as they recorded low to moderate estimates of genetic advance. Studies from association analysis showed that number of productive tillers hill-1 and number of filled grains panicle-1 had a positive significant correlation with yield whereas, seedling mortality and sterility % had a negative significant association with yield. Path analysis revealed that traits number of productive tillers hill-1, number of grains panicle-1 and 1000 grain weight had a positive direct effect on yield. Hence primacy should be given to the above-mentioned traits to develop alkalinity and inland saline tolerant and high yielding rice cultivars. Lines CT 118911, Sahel 177, M 202 and KPS 10654 were found to be promising entries and can be used tolerant parents in the breeding programme. Three principal components combined could explain 68.86% of the total variation.

An insight into variability and association among yield and its components under alkalinity and inland salinity stress in rice (Oryza sativa L.)

An insight into variability and association among yield and its components under alkalinity and inland salinity stress in rice (Oryza sativa L.)

Chitosan Nanoparticles as Seed Priming Agents to Alleviate Salinity Stress in Rice (Oryza sativa L.) Seedlings

Nanoparticle-based seed priming has opened new avenues in crop science due to their plant growth promoting potential. Similarly, biopolymers such as chitosan (CS) are widely studied as seed priming agents due to the biodegradable and biocompatible nature, ability to enhance germination percentage and overall seedling health. Therefore, priming with chitosan nanoparticles (CNPs) is a promising tool to enhance overall plant health. Here, we studied the effect of nanopriming with CNPs or CS (50 µg/mL) on morphological, physiological, and biochemical parameters of rice seedlings, grown in salinity stress conditions NaCl (0–250 mM). CNPs were synthesized using an ionic gelation method and characterized by scanning electron microscopy (50–100 nm), zeta potential analyser (Particle size distribution–373.5 ± 3.7 nm; polydispersity index- > 0.4; zeta potential–45.3 ± 2.5 mV) and profilometry (300–1500 nm hydrodynamic height). Morphological, physiological, and biochemical responses of rice seedlings grown from seeds primed with either CNPs or CS showed a positive effect on germination, seedling vigour, biochemical and antioxidant responses. Seeds primed with CNPs and CS demonstrated significantly higher germination potential and seedling vigour compared to control hydro-primed seeds when grown under increasing NaCl concentrations. These outcomes highlight that CNPs and CS can be used as potential seed priming agents to alleviate salinity stress in rice seedlings. However, further studies are warranted to understand the effect of CNPs and CS seed priming on the overall growth and development of rice plants as well as rice yield.

Differential response of nano zinc sulphate with other conventional sources of Zn in mitigating salinity stress in rice grown on saline-sodic soil

Salinization causes the degradation of the soil and threatening the global food security but the application of essential micronutrients like zinc (Zn), improve the plant growth by stabilizing the plant cell and root development. Keeping in view the above-mentioned scenario, an experiment was conducted to compare the efficiency of conventional Zn fertilizers like zinc sulphate (ZnSO4), zinc ethylene diamine tetra acetic acid (Zn-EDTA) and advance nano Zn fertilizers such as zinc sulphate nanoparticles (ZnSO4NPs), and zinc oxide nanoparticles (ZnONPs) (applied at the rate of 5 and 10 mg/kg) in saline-sodic soil. Results revealed that the maximum plant height (67%), spike length (72%), root length (162%), number of tillers (71%), paddy weight (100%), shoot dry weight (158%), and root dry weight (119%) was found in ZnSO4NPs applied at the rate of 10 mg/kg (ZnSO4NPs-10) as compared to salt-affected control (SAC). Similarly, the plants physiological attributes like chlorophyll contents (91%), photosynthesis rate (113%), transpiration rate (106%), stomatal conductance (56%) and internal CO2 (11%) were increased by the application of ZnSO4NPs-10, as compared to SAC. The maximum Zn concentration in root (153%), shoot (205%) and paddy (167%) found in ZnSO4NPs-10, as compared to control. In the body of rice plants, other nutrients like phosphorus and potassium were also increased by the application of ZnSO4NPs-10 and soil chemical attributes such as sodium and sodium adsorption ratio were decreased. The current experiment concluded that the application of ZnSO4NPs at the rate of 10 mg/kg in salt-affected paddy soil increased the growth, physiology, up take of essential nutrients and yield of rice by balancing the cationic ratio under salt stress.

Salinity alleviator bacteria in rice (Oryza sativa L.), their colonization efficacy, and synergism with melatonin.

In this study, rhizospheric and endophytic bacteria were tested for the alleviation of salinity stress in rice. Endophytic isolates were taken from previous studies based on their salt stress-alleviating traits. The rhizospheric bacteria were isolated from rice and screened based on salt tolerance and plant growth-promoting traits. Molecular identification indicated the presence of class Gammaproteobacteria, Bacillota, and Actinomycetia. Two-two most potential isolates each from rhizospheric and endophytic bacteria were selected for in planta trials. Results showed that microbial inoculation significantly improved germination and seedling vigor under elevated salinity. The confocal scanning laser microscopy showed higher bacterial colonization in inoculated rice roots than in control. Based on this experiment, rhizospheric bacteria Brevibacterium frigoritolerans W19 and endophytic Bacillus safensis BTL5 were selected for pot trial along with a growth-inducing compound melatonin 20 ppm. Inoculation of these two bacteria improved the levels of chlorophyll, proline, phenylalanine ammonia-lyase, catalase, superoxide dismutase, polyphenol oxidase, root-shoot length, and dry weight under elevated salt concentration. The gene expression studies showed modulation of SOD1, CATa, NHX1, and PAL1 genes by the bacterial strains and melatonin application. The inoculation was found to have additive effects with 20 ppm melatonin. This enhancement in dry matter accumulation, compatible solute production, and oxidative stress regulation could help plants in mitigating the ill effects of high salinity. Exploring such a combination of microbes and inducer molecules could be potentially useful in developing stress-alleviating bioformulations.

The Role of Trichoderma in The Early Growth of Rice and Soybean in Saline Soils

Optimizing the use of marginal saline soils to improve food security requires solutions that involve exploiting local potential resources, including the use of biological agents. This research aims to determine the ability of Trichoderma sp. Tc-31 and Aspergillus sp. As-27 to overcome salinity stress in rice and soybean seedlings. Both isolates were tested for their ability to grow in vitro in saline soil. Next, the ability to overcome saline soil stress during germination and initial growth of rice and soybean seedlings was tested. The experiment consisted of three types of treatment, namely the use of As-27, Tc-31, and the use of husks treated with complete basic fertilizer. The average inhibitory power of saline soil against As-27 and Tc-31 was (-)62.50±16.68% and (-) 52±3.54% respectively at 48 days of incubation. The application of biological agents had an effect on germination in rice 94.10-94.46% and soybeans 74.49-77.04%. Biological agents also influence the height growth of rice and soybean seedlings. These two fungal isolates have the potential to be used as biological agents to help rice and soybean seeds overcome salinity stress.

Salicylic acid: To assuage salinity stress at the early seedling stage of rice

Being sessile, plants rely on internal modulation of growth and development to cope up with the changing environmental condition. Among the endogenous regulators, salicylic acid has a major role in restoration of plant growth and providing tolerance towards diverse environmental stresses including salinity stress. Seven genotypes FL 478, ADT 45, ADT 46, ADT 50, CR 1009, KKL(R)1, IW Ponni ) were selected  and treated with 100 ppm SA and sown under saline condition(150 mM NaCl). In this experiment the growth parameters like root length, shoot length, root to shoot ratio and biochemical parameters like total chlorophyll and carotenoids were estimated. When rice seeds treated with 100 ppm of SA, the inhibitory effect of salinity stress on growth parameters were alleviated and significant increase in root to shoot ratio were noticed, which is a very important physiological trait for abiotic stress tolerance. Moreover, there is an increase in both chlorophyll and carotenoid content in seedling stage. This shows that, the increased growth parameters might have attributed to the increase in photosynthetic pigments by exogenous application of salicylic acid under salinity stress in rice.

Applicability of hyperspectral imaging during salinity stress in rice for tracking Na+ and K+ levels in planta.

The ratio of Na+ and K+ is an important determinant of the magnitude of Na+ toxicity and osmotic stress in plant cells. Traditional analytical approaches involve destructive tissue sampling and chemical analysis, where real-time observation of spatio-temporal experiments across genetic or breeding populations is unrealistic. Such an approach can also be very inaccurate and prone to erroneous biological interpretation. Analysis by Hyperspectral Imaging (HSI) is an emerging non-destructive alternative for tracking plant nutrient status in a time-course with higher accuracy and reduced cost for chemical analysis. In this study, the feasibility and predictive power of HSI-based approach for spatio-temporal tracking of Na+ and K+ levels in tissue samples was explored using a panel recombinant inbred line (RIL) of rice (Oryza sativa L.; salt-sensitive IR29 x salt-tolerant Pokkali) with differential activities of the Na+ exclusion mechanism conferred by the SalTol QTL. In this panel of RILs the spectrum of salinity tolerance was represented by FL499 (super-sensitive), FL454 (sensitive), FL478 (tolerant), and FL510 (super-tolerant). Whole-plant image processing pipeline was optimized to generate HSI spectra during salinity stress at EC = 9 dS m-1. Spectral data was used to create models for Na+ and K+ prediction by partial least squares regression (PLSR). Three datasets, i.e., mean image pixel spectra, smoothened version of mean image pixel spectra, and wavelength bands, with wide differences in intensity between control and salinity facilitated the prediction models with high R2. The smoothened and filtered datasets showed significant improvements over the mean image pixel dataset. However, model prediction was not fully consistent with the empirical data. While the outcome of modeling-based prediction showed a great potential for improving the throughput capacity for salinity stress phenotyping, additional technical refinements including tissue-specific measurements is necessary to maximize the accuracy of prediction models.

A novel R3H protein, OsDIP1, confers ABA-mediated adaptation to drought and salinity stress in rice

AimsDehydration responsive element-binding factors (DBFs) have recently emerged as essential components of stress tolerance mechanisms in plants. In this work, we investigated the role of OsDIP1 that operate upstream of DBFs as a regulator of drought and salinity tolerance in rice.MethodsExperiments were conducted on rice plants (Oryza sativa) and included combination of physiological (plant phenotyping) and molecular methods. The latter involved real-time PCR (RT-qPCR); yeast two-hybrid, BiFC assay, GST pull-down, CoIP and firefly luciferase (LUC)/ renilla (REN) assays.ResultsOsDIP1 expression was induced by hydrogen peroxide (H2O2), ABA (abscisic acid), drought (polyethylene glycol treatment), and salt stress. Overexpression of OsDIP1 in rice enhanced drought and salinity tolerance while knocking out OsDIP1 by CRISPR-Cas9 editing resulted in drought and salt sensitive phenotype. The activity and gene expression of antioxidant defense enzymes, superoxide dismutase (SOD), catalase (CAT), was increased in OsDIP1-overexpressed transgenic rice plants, while the content of malondialdehyde (MDA) was decreased. In contrast, the content and gene expression of SODCc2 and CatB, decreased, and the content of MDA was increased in knockout of OsDIP1 rice plants, suggesting that overexpression of OsDIP1 enhances the antioxidant capacity of rice plants. The yeast two-hybrid screening test revealed that OsDIP1 interacted with ZFP36, a key zinc finger transcription factor involved in ABA-induced antioxidant defense. Moreover, OsDIP1 could modulate some key ABA-responsive genes via interacting with ZFP36.ConclusionsIn this work, we show that DIP1 plays a central role in modulating drought and salinity stress tolerance in rice.

The Ability of Silicon Fertilisation to Alleviate Salinity Stress in Rice is Critically Dependent on Cultivar

Silicon (Si) fertiliser can improve rice (Oryza sativa) tolerance to salinity. The rate of Si uptake and its associated benefits are known to differ between plant genotypes, but, to date, little research has been done on how the benefits, and hence the economic feasibility, of Si fertilisation varies between cultivars. In this study, a range of rice cultivars was grown both hydroponically and in soil, at different levels of Si and NaCl, to determine cultivar variation in the response to Si. There was significant variation in the effect of Si, such that Si alleviated salt-induced growth inhibition in some cultivars, while others were unaffected, or even negatively impacted. Thus, when assessing the benefits of Si supplementation in alleviating salt stress, it is essential to collect cultivar-specific data, including yield, since changes in biomass were not always correlated with those seen for yield. Root Si content was found to be more important than shoot Si in protecting rice against salinity stress, with a root Si level of 0.5–0.9% determined as having maximum stress alleviation by Si. A cost–benefit analysis indicated that Si fertilisation is beneficial in mild stress, high-yield conditions but is not cost-effective in low-yield production systems.

Overexpression of a Novel ERF-X-Type Transcription Factor, OsERF106MZ, Reduces Shoot Growth and Tolerance to Salinity Stress in Rice

Transcription factors (TFs) such as ethylene-responsive factors (ERFs) are important for regulating plant growth, development, and responses to abiotic stress. Notably, more than half of the rice ERF-X group members, including ethylene-responsive factor 106 (OsERF106), are abiotic stress-responsive genes. However, their regulatory roles in abiotic stress responses remain poorly understood. OsERF106, a salinity-induced gene of unknown function, is annotated differently in RAP-DB and MSU RGAP. In this study, we isolated a novel (i.e., previously unannotated) OsERF106 gene, designated OsERF106MZ (GenBank accession No. MZ561461), and investigated its role in regulating growth and the response to salinity stress in rice. OsERF106MZ is expressed in germinating seeds, primary roots, and developing flowers. Overexpression of OsERF106MZ led to retardation of growth, relatively high levels of both malondialdehyde (MDA) and reactive oxygen species (ROS), reduced catalase (CAT) activity, and overaccumulation of both sodium (Na+) and potassium (K+) ions in transgenic rice shoots. Additionally, the expression of OsHKT1.3 was downregulated in the shoots of transgenic seedlings grown under both normal and NaCl-treated conditions, while the expression of OsAKT1 was upregulated in the same tissues grown under NaCl-treated conditions. Further microarray and qPCR analyses indicated that the expression of several abiotic stress-responsive genes such as OsABI5 and OsSRO1c was also altered in the shoots of transgenic rice grown under either normal or NaCl-treated conditions. The novel transcription factor OsERF106MZ negatively regulates shoot growth and salinity tolerance in rice through the disruption of ion homeostasis and modulation of stress-responsive gene expression.

The miR528-AO Module Confers Enhanced Salt Tolerance in Rice by Modulating the Ascorbic Acid and Abscisic Acid Metabolism and ROS Scavenging.

The monocot lineage-specific miR528 was previously established as a multistress regulator. However, it remains largely unclear how miR528 participates in response to salinity stress in rice. Here, we show that miR528 positively regulates rice salt tolerance by down-regulating a gene encoding l-ascorbate oxidase (AO), thereby bolstering up the AO-mediated abscisic acid (ABA) synthesis and ROS scavenging. Overexpression of miR528 caused a substantial increase in ascorbic acid (AsA) and ABA contents but a significant reduction in ROS accumulation, resulting in the enhanced salt tolerance of rice plants. Conversely, knockdown of miR528 or overexpression of AO stimulated the expression of the AO gene, hence lowering the level of AsA, a critical antioxidant that promotes the ABA content but reduces the ROS level, and then compromising rice tolerance to salinity. Together, the findings reveal a novel mechanism of the miR528-AO module-mediated salt tolerance by modulating the processes of AsA and ABA metabolism as well as ROS detoxification, which adds a new regulatory role to the miR528-AO stress defense pathway in rice.

Identification and functional prediction of long non-coding RNAs of rice (Oryza sativa L.) at reproductive stage under salinity stress.

Salinity adversely affects the yield and growth of rice (Oryza sativa L.) plants severely, particularly at reproductive stage. Long non-coding RNAs (lncRNAs) are key regulators of diverse molecular and cellular processes in plants. Till now, no systematic study has been reported for regulatory roles of lncRNAs in rice under salinity at reproductive stage. In this study, total80 RNA-seq data of Horkuch (salt-tolerant) and IR-29 (salt-sensitive) genotypes of rice were used and found 1626 and 2208 transcripts as putative high confidence lncRNAs, among which 1529 and 2103 were found to be novel putative lncRNAs in root and leaf tissue respectively. In Horkuch and IR-29, 14 and 16 lncRNAs were differentially expressed in root tissue while 18 and 63 lncRNAs were differentially expressed in leaf tissue. Interaction analysis among the lncRNAs, miRNAs and corresponding mRNAs indicated that these modules are involved in different biochemical pathways e.g. phenyl propanoid pathway during salinity stress in rice. Interestingly, two differentially expressed lncRNAs such as TCONS_00008914 and TCONS_00008749 were found as putative target mimics of known rice miRNAs. This study indicates that lncRNAs are involved in salinity adaptation of rice at reproductive stage through certain biochemical pathways.

Mitigation of Salinity Stress in Rice through Zinc Silicate Application

Mitigation of Salinity Stress in Rice through Zinc Silicate Application

Complementation of ROS scavenging secondary metabolites with enzymatic antioxidant defense system augments redox-regulation property under salinity stress in rice.

The RP-HPLC based comparative quantification of some important redox sensitive phenolic acids and flavonoids revealed overall greater elicitation of chalcone synthase related flavonoid biosynthetic pathway, concomitant with the greater utilization of cinnamic acid for the seedlings of the salinity resistant rice cultivar Patnai as compared to susceptible cultivar IR29 grown under post imbibitional salinity stress (PISS). When compared, the cultivar Patnai further exhibited significantly better antioxidant-coupled redox-regulation by up regulating ascorbate-glutathione pathway and reducing the expression of oxidative deterioration under PISS as compared to its counterpart, the cultivar IR29. A model for redox homeostasis in which complementation of action of ROS scavenging secondary metabolites with enzymatic antioxidant defense at metabolic interface necessary for maintenance of the redox homeostasis to combat salinity stress has been proposed.

Modulation of Growth and Physicochemical Assays in Salt Stressed Rice by Application of Potassium and Salicylic Acid

Salinity stress adversely affected the rice growth, productivity and yield from last few decades. Here, in this study the ameliorative role of foliar application of potassium (K) and salicylic acid (SA) have been investigated against salinity stress in rice. Four rice varieties (Kashmir Basmati, Basmati-370, Super-Basmati and Basmati-515) were exposed to NaCl stress (0, 100mM) and sprayed with SA (0.02%), K (0.1%) and their combination (SA+K) at vegetative and flowering stages. Salinity stress caused reduction in plant fresh and dry weight, plant height, chlorophyll and carotenoids contents, and photosynthetic rate.